Reference is hereby made to other related patent applications which are assigned to the same assignee as the present application; Application of J. Clark entitled "Postage Printing Apparatus Having A Print Head With Replaceable Ribbon Cartridge", Ser. No. 473,842, filed on Mar. 8, 1983; Application of J. Clark and A. Eckert entitled "Postage Printing Apparatus Having a Movable Print Head & A Variable Speed Drum Rotation", Ser. No. 473,843, filed on Mar. 9, 1983; Application of J. Clark entitled "Postage Printing Apparatus Having a Movable Print Head And A Hollow Non-Rotating Support Shaft", Ser. No. 473,831, filed on Mar. 9, 1983; and Application of J. Clark entitled "Postage Printing Apparatus Having A Movable Print Head And A Rotating Print Drum And Ribbon Cartridge", Ser. No. 473,418, filed on Mar. 9, 1983.
This invention relates to postage printing and, more specifically, to a postage meter having a printing drum in which there is incorporated an internal print head for printing the variable data portion of the postage indicia. The movement of the drum through its cycle of operation automatically coordinates the positioning of the internal print head to produce the complete postage indicia.
Postage meters for the application of indicia to a mailpiece are in general use today and thus are well known. The postage meter system prints pre-selected postage onto mailpieces or to adhesive-backed labels which are, in turn, applied to mailpieces. The operator pre-selects the value of the postage to be printed by punching it into a keyboard data entry unit in the system. In other systems, the value of the postage may be automatically selected by scale and/or rate computer. Before using the meter the first time each day, the operator adjusts the date printed by the system to assure it conforms to the date the article is to be mailed. The day may also be automatically set by an associated digital clock. The value and date information is generally regarded as the variable data within the postage indicia to be imprinted on the mailpiece. In addition, fixed data may be and is generally used in the indicia. The fixed data may include the city and state of the originating mailpiece, the meter number, advertisements and other such information. In addition to postage meters, other types of imprinters may use a similar approach to printing control data in a manner similar to postage meters. These include parcel services, tax stamps, check writing services, and the like.
Because some of the data placed in the indicia, such as the date and the value of the postage, must be variable, two printing sections for the indicia are generally combined by the postage meter to print the complete indicia, one section for the fixed data and one for the variable data. One such approach is to use a rotatable printing drum having die plates mounted on its periphery that are adapted to print fixed information. Also located on the periphery of the drum, in the vicinity of the die plates, are a group of settable print wheels which are adapted to print variable information such as the date and postage value. The settable print wheels project through suitable apertures formed in the curved surfaces of the print drum and rotate with the drum. When the drum is rotated or cycled, the die plates and print wheels are suitably inked so as to be capable of imprinting a composite indicia or marking of the fixed and variable data on a mailpiece. In order to vary or pre-set the postage value, a keyboard on the system is used to enter the value desired which automatically varies the operative positions of the print wheels to reflect the desired value. The linkage for setting and changing the print wheels requires an extremely intricate and mechanically complex arrangement. The print wheels are first set to selected rotary positions from the keyboard and then are bodily swung through a rotating printing path in conformance with the movement of the printing drum. The date is normally advanced each day by hand in this type of system. This system provides a way to print fixed and variable data at one printing station with one cycle of the drum.
Another device that carries out the general function described above has the fixed information on a relatively flat die plate-like element with the variable information operably contained within the element. The variable data is implemented by settable print wheels which project through apertures in the die-like element. In this latter device, a mailpiece is placed under the element and a movable platform, which forms the bottom of the letter slot, drives the mailpiece up into the element after the latter has been set at the desired value and inked to create the indicia on the envelope.
In a third type of known device, the print wheels and associated setting linkages described above and used for the variable data are dispensed with and replaced with an electronically controlled ink jet printing device. This type of apparatus is disclosed in U.S. Pat. No. 3,869,986, assigned to Pitney Bowes Inc., Stamford, Conn. In this device, the drum carries an apertured printing die plate which cooperates with a stationary ink jet printing device located in the drum to produce a composite postage imprint. One aperture is for the date and another for the postage amount. The die plate imprints the fixed data. As the apertures in the die plate pass below the ink jet printing device, a plurality of inked droplets are sequentially ejected through the apertures and onto the mailpiece located at the meter print station. An electronic control is provided to actuate the ink jet printing device in timed relation to the movement of the die plate to form the required number and placement of ink drops on the envelope. This forms the variable data in the indicia; that is, the date and postage value. The device relies on a drum position sensor to determine when the die plate apertures are properly aligned with the ink jet printing device and the postage-receiving portion of the mailpiece. A print signal is generated by the sensor and applied to the electronic control to initiate a sequenced projection of the inked droplets.
There has been a need for a compact, low cost and reliable postage meter. It is desirable to produce such a meter which does its printing at one print station so that registration problems are avoided. It is desirable to have the mailpiece compressed sufficiently as the indicia is being applied to it so that print quality standards are met in every cycle. The meter must also meet the usual standards of integrity and security. Although low cost, the meter design desirably should have a high rate of throughput in applying postage indicia for improved convenience and more efficient mail processing.